What term describes the phenomenon where participants experience change due to their expectations of treatment?

The phenomenon where participants experience change due to their expectations of treatment is known as the placebo effect. This effect occurs when individuals perceive an improvement in their condition after receiving a treatment that has no therapeutic value, simply because they believe or expect it will work. This is significant in psychological and medical research as it emphasizes the powerful role that an individual's mindset and expectations can have on their actual health outcomes.

The placebo effect showcases how psychological factors can lead to real physiological changes, highlighting the importance of mental state in healing processes. This effect is often utilized in clinical trials to compare the efficacy of new treatments against a control group receiving a placebo, illustrating the necessity to account for expectation when evaluating treatment effectiveness.